The process of vibration welding utilizes oscillations or vibrations in a particular range of frequencies to bond adjacent plastic or metallic work pieces. Vibration welding can involve moving a work piece under pressure while transmitting oscillations or vibrations therethrough, thus creating heat via surface friction that ultimately bonds or fuses the work piece. A welding tool, referred to alternately as a weld horn or a sonotrode, is directly connected to, or formed integrally with, a weld head. The weld head can include one or more weld buttons. Both plastic and metallic vibration welding processes have tremendous utility in industry, for example in the fusing or bonding of onboard components during the manufacturing of a vehicle.
An exemplary vehicular device that can be manufactured using conventional vibration welding techniques is a multi-cell battery module or battery pack. Such a device can be used as an energy storage system for a variety of applications, including but not limited to the powering of various onboard electronic devices and/or for vehicular propulsion in a hybrid electric vehicle (HEV), an electric vehicle (EV), a plug-in hybrid electric vehicle (PHEV), and the like. While conventional battery designs such as alkaline, voltaic pile, and lead-acid batteries have been used in countless household and industrial applications over the past century, evolving battery types such as nickel cadmium (NiCd), nickel-metal hydride (Ni-MH), lithium ion, and lithium ion polymer batteries have displayed particular utility in emerging vehicle propulsion applications, due in large part to their superior energy densities. Such batteries are often selectively rechargeable either as plug-in style batteries or onboard during a regenerative braking event, depending on the particular configuration of the vehicle.
The long term efficiency, reliability, and durability of a multi-cell battery depends largely on the strength of the welded connections or welded joints between the various cells, and between the various components forming the multi-cell battery. As noted above, conventional vibration welding techniques can be used to form the required welded joints in such a battery, as well as in various other vehicular and non-vehicular components. However, such methods may be limited in certain respects due in part to factors such as mechanical resonance.